Although this invention is primarily directed to an improved incinerator structure adapted to utilize solid fuel such as household and industrial waste, it will be understood that any of various types of combustible, particulate materials may serve as the supply fuel feed for the instant apparatus.
The difficulty of burning certain materials such as refuse is well-known. Refuse often includes a high percentage of slowburning or wet materials which impede combustion and exhibit an erratic burn rate. Furthermore, such compositions vary continuously with the weather, season, area where picked up, conditions under which stored and other uncontrollable and unpredictable variables.
One known method of burning refuse is to divide the incinerator grate into two or three separate treatment zones and, through plenum chambers, provide combustion air under differing parameters to each one, thereby varying the characteristics of the air to suit the combustion needs. Thus, the air in the first zone containing fresh unburned refuse may be heated to dry out the trapped moisture, with combustion possibly not commencing until the refuse has entered the next zone, which is supplied with a different air mix.
Control of combustion in the various zones is generally limited to varying the characteristics of the air flowing to each zone. However, as the thickness of the refuse layer and its characteristics are generally not uniform across any one zone, burning time is longer, dictated by the slowest burning area on the grate.
It is, therefore, desirable to divide the grate surface into more zones and to provide means for independently controlling the combustion in each zone. Furthermore, the control should be as automatic as possible, so that each zone can be monitored and adjusted continuously, in an effort to maximize the efficiency of the burning to obtain the greatest throughput, be it solely an objective to dispose of an input feed material, or alternately to produce a source of energy, such as heated air, water or steam from the burning operation.